Laminin

Laminin is an important protein found in the extracellular matrix, the sheets of protein that form the substrate of all internal organs also called the basement membrane. It has four arms that can bind to four other molecules. The three shorter arms are particularly good at binding to other laminin molecules, which allows them to form a flexible woven sheet. The long arm is capable of binding to cells, which helps anchor the actual organs to the membrane.

The laminin protein is made up of three separate parts, called the A, B1, and B2 chains. This gives the large protein molecule a total of six "ends", which each can bind to a specific type of molecule. The three shorter arms each form a coil with another laminin molecule, forming a network of protein that can stretch and bend. The long arm can bind to a cell, linking the cell to the extracellular matrix, and thus to other cells.

Laminin and other ECM proteins are secreted and incorporated into cell-associated extracellular matrices. Laminin is vital for the maintenance and survival of tissues. Defective laminins can cause muscles to form improperly, leading to a form of muscular dystrophy, lethal skin blistering disease (Junctional epidermolysis bullosa) and defects of the kidney filter (Nephrotic syndrome).

Structure

Laminins are high-molecular weight (~400 to ~900 kDa) proteins of the extracellular matrix. They are a major component of the basal lamina (one of the layers of the basement membrane), a protein network foundation for most cells and organs. The laminins are an important and biologically active part of the basal lamina, influencing cell differentiation, migration, and adhesion.

Function

Laminins are cell-adhesive glycoproteins that can create a scaffold for cells, allowing them to move and grow. They also play a crucial role in cell survival, proliferation and differentiation. Laminins are vital for the formation and function of the basement membrane and function in the cell adhesion, growth, migration, and differentiation of cells.

Clinical significance

Mutations in laminin genes are associated with congenital muscular dystrophy, junctional epidermolysis bullosa, laryngoonychocutaneous syndrome, and Pierson syndrome. Laminins are being researched for their use in regenerative medicine, especially in relation with diseases affecting muscle tissue.

See also

• Extracellular matrix
• Basement membrane
• Cell adhesion
• Muscular dystrophy
• Junctional epidermolysis bullosa
• Nephrotic syndrome

Laminin Resources
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